Creating water gaps

[bigyihsuan]

I want to create water gaps, similar to the ones found in the Appalachians.

According to Wikipedia, water gaps happen when a river is older than the surrounding, uplifted land, leading to cutting a notch into the ridges it passes through.

I have a sketch world that somewhat does this: an Erosion node with minimal erosion settings, with uplift turned on, and a mask of ridges. This leads to this sort of water gap as a result, but it leaves these nasty spikes where the uplift touches the river:

water gap.tmd (260.5 KB)

Any other ideas?

[Tomatiy]

River node with big Valley width or big Bank width and you done

With Reach Creator you may craft own settings for better gap and river shape

default Create Water not best in meaning of wide rivers configuration abilities

but i may be wrong

[bigyihsuan]

@Tomatiy

River node with big Valley width or big Bank width and you done

This works, but the issue is that the River device is a manual device (you need to place the rivers manually). Ideally I want this this to work with Create Water instead, so I can randomize terrain and have it work each time.

[bigyihsuan]

Influence Noise to flow in general direction

Procedurally control of continent-level features is a pretty challenging thing! I’m guessing what you’re looking for here is to make something that looks like the tectonically-compressed folds that become mountain ranges on the edges of continents. If you can deal with having only a single direction that the noise is folded in, you can use a Placement device and turn up the anisotropy to create directional noise: [image] In Build 4044, out imminently, the Scatter device gains the ability to…

The above combined with this would make some great Appalachian “ridge-and-valley” sort of terrain:

[bigyihsuan]

I’ve done some testing with the sample world, and managed to combine it with a repeating gradient to make these ridges:

and a “background” terrain with water to put it onto:

Now, my first thought for combining them together is to use an erosion node, with uplift set and the ridges as a mask:

However, this leads to the rivers cutting sharp vertical cliffs into the ridges:

Any ideas on eroding the parts next to the rivers into nothingness?

The main issue is that, if the river predates the uplift, then the river should be eroding the uplift while it’s occurring, which the erosion uplift option doesn’t seem to do. Ideally, the ridges near rivers should be forced down to 45 degree slopes.

[HYLK]

The device that can do this is the Thermal Weathering device. It can carve those slopes out for you. However, it applies it globally, so we need a dynamic mask.

What you probably need to do, is create a mask based on the river tributary, by expanding it. Then, use that mask to blend the TW effect.

[bigyihsuan]

So something like this?

If this is what you’re thinking of, it still leaves fairly steep slopes.

water gap.tmd (952.8 KB)

[HYLK]

Yes that’s the idea! Set the mass balance to -1 for a stronger cutting effect, and the angle of repose to 45 if you want a 45 deg shape. If still unclear, I’ll see what I can do during the weekend with the file you attached to your post!

[bigyihsuan]

Hmm. Setting mass balance to -1 is leads to these holes appearing sometimes:

Setting it to more than -1 removes these holes.

Sidenote: I can create different river courses by applying Flow Restructure and Create Water twice, which is neat.